Aliens
Pumpkinhead
Cursed
Bad moon
Lord of the rings Two towers and Return of the king are best
Castle freak
Jack Brooks monster slayer
Underworld
the great yokai war
Splinter (really good movement)
Without taking a looong time those pop into my mind. But dont limit yourself to horror movies. I encourage my actors to watch animal documentaries, watch lions stalking wildebeasts and leopards stalking gazelles. Watch all big predators and scary animals. If you can trigger the primal prey animal in your guests then you win. Posture and movements from animals can be mimiced and are very effective.
Allen H

Watching a film of a predator, how it moves, how it lunges to effect the kill.....Oh, wait, maybe I have to see more than just films about big snakes?
The only snakey part of me can't quite do those things...anymore.
Having the diamond-back pattern tatooed on me would hurt ALOT TOO!
(How small do they make those needles?)

I think many of those involved with movies have studied animals. There are several characters/creatures that I can recall walking around 10-30 feet away from the intended victim in a manner similar to a predator, just kind of studying the victim. Like a lion, it could have just attacked but there was something very creepy about it taking its time.

This is a great thread. I have been watching tons of haunt videos lately, and it looks like the actor-popping-out-and-surpising/scaring-the-victim thing is overdone. That's the standard in haunts, of course, but how much is enough? I have been through some very long haunts where there are dozens of such scares. After the first few it begins to lose its effectiveness, even if the theme of the rooms change. "Boo" or "Arrr" only works so many times. But walking into a setting and having the actor start to circle you from a short distance away, with head cocked to one side a little like he's sizing you up, that can be just downright chilling.

Awesome suggestion Allen, I am so going to get in touch with my inner animal! We have dress rehearsal on 9/25 and I'm going give this approach a try. I wonder about insect predators and how they stalk their prey....I would like to go with a completely nonhuman scarefactor and Jim I think to have a snake pattern done correctly you would need to go traditional, a hammer and sharpened boar tusk.

Detoro and many other directors and writers many times studied the animal world for inspiration so Allen's suggestion is really good. If you portraying a more human like killer I suggest watching the orginal Psycho, american psycho, house of 1000 corpses, and texas chainsaw massacre the orginal and even the remake as long as it has the former drill seargent in it. No matter what you are doing make sure you show intent in your eyes and actions even when wearing a mask alot of people will react to it because it will translate to how you move. Just don't go to far down the rabbit hole or you may have a hard time coming back >.<

If your wondering if you have intent if you can look at some one with no makeup on and with out saying a word but by just using your body face and eyes and convince them your about to remove their soul through their nostrils you got it.
If your a playing a victim if you can convince someone of your fear with out using your voice then you got it, because fear is like a plague and spreads swiftly even to those unsuspecting. after this you add in the vocals and you have a convincing performance that can help your patrons suspend their usual grasp on reality.

Sits in a comfortable chair, in a well lit, large room, with other people, the room is air-conditioned, clean.
The Actual predator can't really be picked out from the others in the room.
He makes up his mind, pushes the button..minutes later there is a small explosion on the other side of the planet, some people died.
The scariest predator you will ever not see in a zoo or a nature film, or ever see at all.